Vehicle structural body members, such as exterior rocker panels and spoilers, may improve the appearance and/or aerodynamics of a vehicle. Improving vehicle aerodynamics is one way to improve vehicle fuel economy. High forces may be exerted on structural body members due to aerodynamic forces or other load forces.
Increasing the depth of an exterior rocker panel may improve the vehicle's relative aerodynamics by a reduction of up to 12 drag counts. As the depth of the rocker molding is increased, it protrudes further from the vehicle and people may increasingly use it as a step to enter and exit the vehicle or to access the area above their vehicle to load cargo onto luggage racks or clean vehicle surfaces. As such, rocker panels may be designed to support the weight of a person standing on the rocker panel. Increased rocker panel depth may also increase torque on the rocker panel as weight may be exerted on the rocker panel remotely from where the rocker panel is attached to the vehicle.
Spoilers are subjected to high aerodynamic forces, especially when the vehicle is moving at high speeds. In addition, spoilers may be used as a handle for opening and closing trunk lids and hatchback doors, or as a grab handle. As such, spoilers may be designed to support aerodynamic and non-aerodynamic load forces.
Currently rocker panels on most trucks and sport utility vehicles have a multi-piece construction that includes a metal structural member attached to the side or frame of the vehicle and a cap member attached to the structural member for appearance and/or aerodynamics. The metal structural member is typically extruded aluminum and the cap piece is typically a thin molded plastic. Attempts to mold such components as one piece structures having structural ribs or lattice work have been unsuccessful due to undesirable sink marks, flow lines and other imperfections on the visible surface of the structural body member or weak parts that are not capable of handling associated load forces.